ML20248D496
| ML20248D496 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 03/29/1989 |
| From: | NRC |
| To: | |
| Shared Package | |
| ML20248D490 | List: |
| References | |
| NUDOCS 8904110493 | |
| Download: ML20248D496 (4) | |
Text
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'3/4.2 POWER DISTRIBUTION LIMITS 3/4.2.1 AVERAGE PLANAR LINEAR HEAT GENERATION RATE LIMITING CONDITION FOR OPERATION 3.2.1 All AVERAGE PLANAR LINEAR HEAT GENERATION RATES (APLHGRs) for each type of fuel as a function of AVERAGE PLANAR EXPOSURE shall not exceed the limits shown in Figures 3.2.1-1, 3.2.1-2, 3.2.1-3, 3.2.1-4, 3.2.1-5, 3.2.1-6, 3.2.1-7 and 3.2.1-8.*
The limits of Figures 3.2.1-1, 3.2.1-2, 3.2.1-3, 3.2.1-4, 3.2.1-5, 3.2.1-6, 3.2.1-7 and 3.2.1-8 shall be reduced to a value of 0.84 times the two recirculation loop operation limit when in single loop operation.
APPLICABILITY:
OPERATIONAL CONDITION 1, when THERMAL POWER is greater than or equal to 25% of RATED THERMAL POWER.
ACTION:
With an APLHGR exceeding the limits of Figure 3.2.1-1, 3.2.1-2, 3.2.1-3, 3.2.1-4, 3.2.1-5, 3.2.1-6, 3.2.1-7 or 3.2.1-8, initiate corrective action l
within 15 minutes and restore APLHGR to within the required limits within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> or reduce THERMAL POWER to less than 25% of RATED THERMAL POWER within the next 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.
SURVEILLANCE RE0VIREMENTS 4.2.1 All APLHGRs shall be verified to be equal to or less than the limits determined from Figures 3.2.1-1, 3.2.1-2, 3.2.1-3, 3.2.1-4, 3.2.1-5, 3.2.1-6, 3.2.1-7 and 3.2.1-8:
a.
At least once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, b.
Within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> after completion of a THERMAL POWER increase of at least 15% of RATED THERMAL POWER, and Initially and at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> when the reactor is operating c.
with a LIMITING CONTROL ROD PATTERN for APLHGR.
1 d.
The provisions of Specification 4.0.4 are not applicable.
l l
l l
- The limits on Figures 3.2.17 and 3.2.1-8 are to be used only for manual calculations.
RIVER BEND - UNIT 1 3/4 2-1 Amendment No. Z2, 31, 33 8904110493 890329 9
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10 20 30 40 50 AVERAGE PLANAR EXPOSURE (GWd/t) 4 n
FIGURE 3.2.1 1 MAXIMUM AVERAGE PLANAR LINEAR HEAT GENERATION RATE (MAPLHGR) l YERSUS AVERAGE PLANAR EXPOSURE BPBSRB094 l
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RIVER BEND - UNIT 1 3/42-2 Amendment No.12
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3 /4. 2 POWER DISTRIBUTION LIMITS BASES The specifications of this section assure that the peak cladding temper-ature following'the postulated design basis loss-of-coolant accident will not exceed the 2200 F limit specified in 10 CFR 50.46.
3/4.2.1 AVERAGE PLANAR LINEAR HEAT GENERATION RATE
^
The peak cladding temperature (PL?) following a postulated 1oss-of-coolant accident is primarily a function of the average heat generation rate of all the rods of a fuel assembly at any axial location and is dependent only second-arily on the rod to rod power distribution within an assembly. The peak clad
_ temperature is calculated assuming a LHGR for the highest powered rod which is equal to or less than the design LHGR corrected for densification. This LHGR times 1.02 is used in the heatup code along with the exposure-dependent steady state gap conductance and rod-to-rod local peaking factor. The Technical Specification AVERAGE PLANAR LINEAR HEAT GENERATION RATE (APLHGR) is this LHGR of the highest powered rod divided by its local peaking factor. The limiting value for APLHGR is shown in Specification 3.2.1.
l The daily requirement for calculating APLHGR when THERMAL POWER is greater than or equal to 25% of RATED THERMAL POWER is sufficient since power distribu-tion shifts are very slow when there have not been significant power or control red changes.
The requirement to calculate APLHGR within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> after the com-pietion of a THERMAL POWER increase of at least 15% of RATED THERMAL POWER ensures thermal limits are met after power distribution shifts while still allotting time for the power distribution to stabilize. The requirement for calculating APLHGR after initially determining a LIMITING CONTROL ROD PATTERN exists ensures that APLHGR will be known following a changs in THERMAL POWER or power shape that could place operation into a condition axceeding a thermal limit.
~
The calculational procedure used to establish the APLHG^A shown in Specification 3.2.1 is based on a loss-of-coolant accident analysis. The a
w analysis was performed using General Electric (GE) calculational models which are consistent with the requirements of Appendix K to 10 CTR 50. A complete discussion of each code employed in the analysis is presented in NEDE-20566(1).
Differences in this analysis compared to previous analyses can be broken down as follows.
a.
Input Chances 1.
Corrected vaporization Calculation - Coefficients in the vaporization correlation used in the REFLOOD code were corrected.
2.
Incorporated more accurate bypass areas - The bypass areas in the top guide were recalculated using a more accurate technique.
RIVER BEND - UNIT 1 B 3/4 2-1 Amendment No.12.33 u__-__ _ _ _ _ _ _
POWER DISTRIBUTION LIMITS I
BASES i
AVERAGE PLANAR LINEAR HEAT GENERATION RATE (Continued) 3.
Corrected guide tube thermal resistance.
4.
Correct heat capacity of reactor internals heat nodes.
b.
Model Change 1.
Core CCFL pressure differential - 1 psi - Incorporate the assumption that flow from the bypass to lower plenum must overcome a 1 psi pressure drop in core.
2.
Incoporate NRC pressure transfer assumption - The assumption used in the SAFE-REFLOOD pressure transfer when the pressure is increasing was changed.
A few of the changes affect the accident' calculation irrespective of CCFL.
These changes are listed below.
a.
Input Change 1.
Break Areas - The DBA break area was calculated more accurately.
b.
Model Change 1.
Improved Radiation and Conduction Calculation - Incorporation of CHASTE-05 for heatup calculation.
A list of the significant plant input parameters to the loss-of-coolant accident analysis is presented in Bases Table B 3.2.1-1.
For plant operation with a single recirculation loop, the MAPLHGR limits of figures 3.2.1-1 through 3.2.1-8 are multiplied by 0.84.
The constant l
factor 0.84 is derived from LOCA analyses initiated from single recirculation loop operation to account for earlier boiling transition at the limiting fuel mode compared to the standard LOCA evaluations.
3/4.2.2 APRM SETPOINTS The fuel cladding integrity Safety Limits of Specification 2.1 were based on a p er distribution which would yield the design LHGR at RATED THERMAL POWER.
The flow biased simulated thermal power-high scram trip setpoint and the flow biased neutron flux-upscale control rod block trip setpoints of the APRM instru-c.
ments must be adjusted for both two recirculation loop operation and single recirculation loop operation to ensure that MCPR does not become less than the fuel cladding safety limit or that > 1% plastic strain does not occur in the degraded situation.
The scram settings and rod block settings are adjusted in accordance with the formula in this specification, when the combination of THERMAL POWER and CMFLPD indicates a peak power distribution, to ensure that an LHGR transient would not be increased in degraded conditions.
RIVER SEND - UNIT 1 B 3/4 2-2 Amendment No. If, 31, 33 f